Although state police reported as of about 7:30 a.m. that the scene has been cleared, westbound traffic has backed up from Exit 3 to at least Exit 5, which serves Route 20.

State Police Sgt. Alan Joubert, who is attached to the Springfield barracks, said at least four vehicles were towed from the scene and that the state Department of Transportation has since treated the interstate.

Ice is also the suspected cause of a vehicle rollover in the northbound lanes of Interstate 91, just before Exit 25 in Deerfield.

Trooper Nick Pellegrino, who is attached to the Shelburne Falls barracks, said a person suffered minor injuries.

The rollover was reported about 6 a.m. Along with black ice, early commuters in the northern stretches of Interstate 91 dealt with heavy fog, Pellegrino said. That roadway has since been treated as well.

Ice was also blamed for early morning truck crash in the northbound lanes of Interstate 91 in Holyoke. City police said there were no reported injuries in the crash, which involved a smaller truck and trailer.